Probiotic properties of lactic acid bacteria
The term probiotics is derived from the Greek word ‘pro’ means for and ‘bio’ means life and had assumed several meanings over the years. Lilly and Stillwell were the first one to introduce the term probiotics in the year 1965 to describe the growth promoting factors produced by the microorganisms. However over the years, the term probiotics has been linked to several definitions.
As per the version of Parker, probiotics can be defined as those organisms and substances, which contribute to the intestinal microbial balance. Later, Fuller redefined probiotics as foods containing live microorganisms, which actively enhance the health of consumers by improving the balance of microflora in the gut, when ingested live in sufficient numbers. Later, Salminen revised the definition of probiotic as a live microbial culture or cultured dairy product which beneficially influences the health and nutrition of the host. Type of probiotics Many types of bacteria have been used as probiotics since time immemorial. They mainly consist of lactic acid producing bacteria (Lactobacilli, Streptococci, Enterococci and Lactococci). Bifidobacteria, Bacillus species, yeasts like Saccharomyces species too find a place in the long list of probiotics. The mode of ingestion is either through food or in a non food format. The probiotics generally subsist in the stomach |
How to select the probiotics and what are their ideal properties?
The ideal property of a probiotic is its ability to impart beneficial effect and not harm to the consumer. Hence, it is necessary that all the strains must be carefully and thoroughly studied prior to their utilization in humans or animals and should be having confirmed genetically regarded as safe (GRAS). The following are some of the properties, the probiotics are supposed to possess. They are
- Colonization or adhesion properties.
- Human origin
- Good in vitro development
- Ability of cells to produce metabolites and enzymes
- Stability in gastric juices and bile
- Production of antimicrobial substances
- Safe for clinical use
- Antagonistic action against noted pathogenic bacteria and / or viruses.
- Factors that influence the strain survival during / after administration and
- No adverse interactions with host especially, in terms of pathogenicity.
The yoghurt prepared using traditional probiotics such as Lactobacillus delbrueckii ssp. bulgaricus and Streptococcus salivarius ssp. thermophilus is claimed to provide some health benefits. The problem is that they are not natural inhabitants of the intestine and do not normally survive under acidic conditions and bile concentrations usually found in the gastro intestinal tract. Hence, the yoghurt, to be considered as a probiotic, both Lactobacillus bulgaricus and Streptococcus thermophilus along with bifidobacteria and Lactobacillus casei are usually incorporated as a dietary adjunct. It has been found that for a probiotic to be effective, it should be consumed at a concentration of 100 million to 1 billion viable colony forming units (cells) per ml daily.